Search results for "InSe"

Black fungus-gnats in deciduous forest habitat in northern Europe, with the description of <i>Bradysia arcula</i> sp. n. (Diptera: Sciari…

2007

The sciarid fauna of a deciduous forest in Kivijärvi Nature Reserve, southern Finland, was studied. In all, 58 species were found in a material of 247 specimens, collected with Malaise traps. The material included the following species new to the Finnish and North European fauna: Corynoptera postforcipata Rudzinski, Leptosciarella juniperi (Mohrig & Blasco-Zumeta), Leptosciarella subcoarctata Mohrig&Menzel, Leptosciarella yerburyi (Freeman), Phytosciara macrotricha (Lengersdorf) and Sciara nursei Freeman. Bradysia arcula sp. n., found also in two other localities in Finland, is described, and a key to the Finnish species of the Bradysia praecox group is provided

Implosión democrática / 1

2008

Insertion of isocyanides into the 2-one-1-propyl—palladium(II) bond: A convenient synthetic route to C1-palladated 1-amino-3-one-1-butene compounds

1984

Abstract Migratory insertion of isocyanides CNR (R = p -C 6 H 4 OMe, Me) into the palladium—carbon σ bond of trans -[PdCl(CH 2 COMe)(PPh 3 ) 2 ] (I) yields the 1-amino-3-one-1-butenyl complexes trans -[PdCl{C(NHR)CHCOMe}(PPh 3 ) 2 ] (IIa, R = p -C 6 H 4 OMe; IIb, R = Me), which have been characterized by IR, 1 H and 31 P NMR spectra. The reaction of IIa with nickel acetate gives a diamagnetic bischelate complex of the type [Ni(ON) 2 ] , in which the deprotonated 1-amino-3-one-1-butenyl moiety acts as a bidentate O,N ligand.

Multiple Roles of Isocyanides in Palladium-Catalyzed Imidoylative Couplings: A Mechanistic Study

2016

International audience; Kinetic, spectroscopic and computational studies examining a palladium-catalyzed imidoylative coupling highlight the dual role of isocyanides as both substrates and ligands for this class of transformations. The synthesis of secondary amides from aryl halides and water is presented as a case study. The kinetics of the oxidative addition of ArI with RNC-ligated Pd-0 species have been studied and the resulting imidoyl complex [(ArC=NR)Pd(CNR)(2)I] (Ar=4-F-C6H4, R = tBu) has been isolated and characterized by X-ray diffraction. The unprecedented ability of this RNC-ligated imidoyl-Pd complex to undergo reductive elimination at room temperature to give the amide in the p…

Introduzione

2015

Già da qualche decennio, in Italia, si assiste a una progressiva marginalizzazione dell’insegnamento della storia nei programmi didattici. Questo fenomeno corrisponde alla condizione generale della cultura contemporanea e, nello specifico, all’affermarsi di un indirizzo problem-solving contrassegnato da un’enfasi tecnico-scientifica. Una deriva che non riguarda soltanto le università italiane, ma prende avvio nelle scuole superiori. Lo dimostra il recente crollo delle iscrizioni al liceo classico, che alcuni considerano l’inizio dell’ormai imminente scomparsa d’una tradizione riconducibile agli studia humanitatis del Quattrocento, mentre altri una benefica liberazione, un residuo del passat…

Determination of carbamate residues in fruits and vegetables by matrix solid-phase dispersion and liquid chromatography-mass spectrometry.

2000

Abstract Thirteen carbamates were analysed in orange, grape, onion and tomatoes by matrix solid-phase dispersion (MSPD) followed by liquid chromatography–mass spectrometry (LC–MS). Electrospray (ES) and atmospheric pressure chemical ionisation (APCI) were compared and both gave similar results in terms of sensitivity and structural information because at 20 V fragmentor voltages the fragmentation is minimal. The efficiency of different solid-phases (C18, C8, cyano, amine and phenyl) for the MSPD was compared. Mean recoveries using C8 varied from 64 to 106% with relative standard deviations of 5–15% in the concentration range of 0.01–10 mg kg−1. Matrix constituents did not interfere signific…

Analysis of organophosphorus pesticides in honeybee by liquid chromatography-atmospheric pressure chemical ionization-mass spectrometry.

2001

Pesticides applied in extended agricultural fields may be controlled by means of bioindicators, such as honeybees, in which are the pesticides bioaccumulate. Liquid chromatography-atmospheric pressure chemical ionization-mass spectrometry (LC-APCI-MS) experiments with positive (PI) and negative (NI) ion modes were optimized for the analysis of 22 organophosphorus pesticides in honeybee samples. The extraction required 3 g of sample, which was extracted with acetone. The extract was purified with coagulating solution and reextracted with Cl(2)CH(2). Pesticides studied could be detected by both ionization modes except for parathion, parathion-methyl, and bromophos, which did not give signals …

Determination of organophosphorus pesticides in honeybees after solid-phase microextraction.

2001

A method based on solid-phase microextraction (SPME) followed by gas chromatography with nitrogen-phosphorus detection was developed for the purpose of determining 18 organophosphorus pesticide residues in honeybee samples (Apis mellifera). The extraction capacities of polyacrylate and poly(dimethylsiloxane) fibers were compared. The main factors affecting the SPME process, such as the absorption time profile, salt, and temperature, were optimized. The method involved honeybee sample homogenization, elution with an acetone:water solution (1:1) and dilution in water prior to fiber extraction. Moreover, the matrix effect on the extraction was evaluated. In samples spiked at the 0.2 mg kg(-1) …

Determination of abamectin in citrus fruits by liquid chromatography-electrospray ionization mass spectrometry.

2000

Liquid chromatography coupled to electrospray mass spectrometry (LC-ES-MS) with positive ion detection was used to determine abamectin in oranges. MS conditions were optimized to achieve maximum sensitivity. The main ion for abamectin was [M+Na]+ at a fragmentor voltage of 180 V. Abundant structural information can be obtained at different fragmentor voltages. The detection limit for the standard solution was 12 pg injected, and good linearity and reproducibility were observed. Abamectin residues were extracted using matrix solid-phase dispersion. Orange samples were homogenized with C18 bonded silica placed onto a glass column and eluted with dichloromethane. Recoveries of the abamectin fr…

Educational Pathways and Gender Differences in Labor Market Entry in France

2015

International audience